CPMulator is a program to emulate the

CP/M CP/M, originally standing for Control Program/Monitor and later Control Program for Microcomputers, is a mass-market operating system created in 1974 for Intel 8080/ 85-based microcomputers by Gary Kildall of Digital Research, Inc. Initial ...

operating system under x86 DOS. The program was developed in 1984 by Keystone Software Development. The company was owned and operated by Jay Sprenkle. The NEC V20 processor released that year was guaranteed to be hardware compatible with the Intel 8088. After reviewing the instruction timing of the math operations and instruction addressing hardware it was determined it could slightly speed up existing 8088 based

IBM PC The IBM Personal Computer (model 5150, commonly known as the IBM PC) is the first microcomputer released in the IBM PC model line and the basis for the IBM PC compatible de facto standard. Released on August 12, 1981, it was created by a team ...

machines. Keystone software started advertising "PC Speedup Kits" in ''

PCWeek ''eWeek'' (''Enterprise Newsweekly'', stylized as ''eWEEK''), formerly PCWeek, is a technology and business magazine. Previously owned by QuinStreet; Nashville, Tennessee marketing company TechnologyAdvice acquired eWeek in 2020. The print ed ...

'' magazine. The CPU was socketed in IBM PC's so it could easily be replaced. In practice most programs received a 5% speed increase but those that were math intensive were much improved. One customer reported his

monte carlo simulation Monte Carlo methods, or Monte Carlo experiments, are a broad class of computational algorithms that rely on repeated random sampling to obtain numerical results. The underlying concept is to use randomness to solve problems that might be determini ...

of a nuclear reactor was so much faster that he "double checked the results because he couldn't believe it was finished." CPMulator was developed after the release of the V20. The processor was also able to emulate the Intel 8080 instruction set in hardware. This opened the possibility of running older code on the new IBM machines. CPMulator was designed to modify CP/M binaries to make them run as if native 8088 DOS programs. The code to put the CPU in emulation mode was prefixed to each CP/M executable. Any calls to the CP/M operating system were intercepted and translated to DOS operating system calls. The program would leave 8080 emulation mode, make the operating system call, translate the results to CP/M standards and returned to emulation mode and continue the original program. The product went out of production after AT class machines became prevalent and NEC produced no V series pin for pin compatible version of 80286 processor.

References

{{Digital Research CP/M Microcomputer software